一个效率很高的汉字转拼音首字母的函数

create function [dbo].[fn_getpy2](@Str varchar(500)='')
returns varchar(500)
as
begin
 declare @strlen int,@return varchar(500),@ii int
 declare @n int,@c char(1),@chn nchar(1)

 select @strlen=len(@str),@return='',@ii=0
 set @ii=0
 while @ii<@strlen
 begin
  select @ii=@ii+1,@n=63,@chn=substring(@str,@ii,1)
  if @chn>'z'
  select @n = @n +1
     ,@c = case chn when @chn then char(@n) else @c end
   from(
    select top 27 * from (
     select chn = '吖'
     union all select '八'
     union all select '嚓'
     union all select '咑'
     union all select '妸'
     union all select '发'
     union all select '旮'
     union all select '铪'
     union all select '丌'  --because have no 'i'
     union all select '丌'
     union all select '咔'
     union all select '垃'
     union all select '嘸'
     union all select '拏'
     union all select '噢'
     union all select '妑'
     union all select '七'
     union all select '呥'
     union all select '仨'
     union all select '他'
     union all select '屲'  --no 'u'
     union all select '屲'  --no 'v'
     union all select '屲'
     union all select '夕'
     union all select '丫'
     union all select '帀'
     union all select @chn) as a
    order by chn COLLATE Chinese_PRC_CI_AS 
   ) as b
  else set @c=@chn
  set @return=@return+@c
 end
 return(@return)
end